Fixes #1483

Remove support for 'disabled' in plugin folder

This `$conf['pluginmanager']` setting was especially for disabling of
pluginmanager in farms. (see also commit c45608df )

remaining folders with .disabled in the foldername are displayed in
extension manager with rename warning.

The opera work around is still needed though! O_o

Standardized node.textContent is available since IE9

Remove old browser support

Our minimum PHP version requirement is now over 5.3, so this workaround is
not needed anymore. See also c9454ee3

Translation update (fr)

Close #1323

Add generic 3way merge capability

Show change of file sizes in the revision log

add rel=noopener to links opening in new window

Textareas use CRLF, but internally we use LF.

Add an ACL check in page_findnearest, fix #1369

Translation update (es)

@scrutinizer-notifier noticed that the $pageid might be false when
page_findnearest looks for it.

Make cleaning optional in mediaFN, keep as default

reusing the diff colors as suggested by @selfthinker

As in wikiFN cleaning the id should be optional, but still the default, in mediaFN as well.

when a form was submitted with an empty input, that data should still
overwrite the preset value.